When a man is found dead in an industrial cake mixer, Castle and Beckett trace the murder to an Irish gang in Staten Island and a beautiful bar owner named Siobhan O'Doul. Much to everyone's surprise, Detective Ryan has a complicated history with Siobhan and the Staten Island crime family from his days working undercover in narcotics. When the case hits a dead end, Ryan must go back undercover to expose the killer, complicating his relationship with his wife.

Recap

The episode begins with Castle telling Kate that he wants to eat something sweet and by “sweet” he means her. Kate quickly changes the subject and tells him that he was sleep talking last night and he mentioned the name Jordan, fourteen times. Castle tells her that the name means nothing to him. Kate is not convinced. At that very moment, Kate gets a call about the recent murder and they both leave to check the crime scene. They arrive at a bakery. Lanie tells them that the victim was shot at the back and then fell into the mixer. She also says that before he was shot, he did struggle with his attacker and she has found some fibers caught up in the victim’s watch. ..